1 Features

1? Space-Saving SOT-23 Package

? Input Voltage Range of 3 V to 5.5 V

? Output Voltage Range of 0.6 V to 4.5 V

? 1.5-A Output Current

? High Switching Frequencie

– 1.6 MHz (LM2831X)

– 0.55 MHz (LM2831Y)

– 3 MHz (LM2831Z)

? 130-mΩ PMOS Switch

? 0.6-V, 2% Internal Voltage Reference

? Internal Soft Start

? Current Mode, PWM Operation

? Thermal Shutdown

? Overvoltage Protection

2 Applications

? Local 5 V to Vcore Step-Down Converters

? Core Power in HDDs

? Set-Top Boxes

? USB Powered Devices

? DSL Modems

3 Description

The LM2831 regulator is a monolithic, high-

frequency, PWM step-down DC-DC converter in a 5- pin SOT-23 and a 6-Pin WSON package. The

LM2831 provides all the active functions to provide

local DC-DC conversion with fast transient response

and accurate regulation in the smallest possible PCB area. With a minimum of external components, the

LM2831 is easy to use. The ability to drive 1.5-A

loads with an internal 130-mΩ PMOS switch using

state-of-the-art 0.5-μm BiCMOS technology results in

the best power density available. The world-class

control circuitry allows on-times as low as 30 ns, thus

supporting exceptionally high frequency conversion

over the entire 3 V to 5.5 V input operating range,

down to the minimum output voltage of 0.6 V. Switching frequency is internally set to 550 kHz, 1.6

MHz, or 3 MHz, allowing the use of extremely small

surface mount inductors and chip capacitors. Even

though the operating frequency is high, efficiencies of

up to 93% are easy to achieve. External shutdown is included, featuring an ultra-low standby current of 30

nA. The LM2831 utilizes current-mode control and

internal compensation to provide high-performance

regulation over a wide range of operating conditions.

Additional features include internal soft-start circuitry

to reduce inrush current, pulse-by-pulse current limit,

thermal shutdown, and output overvoltage protection.